Anthropometry Flashcards
Why measure body compositions?
To evaluate growth and/or nutritional status of individuals or populations e.g. detection of malnutrition, obesity, or even specific nutrient deficiencies.
To assess the effect of a certain conditions or disease state
To determine the effect of health interventions or look for associations between body composition and other factors
What is the only direct method uses to measure body composition?
The only direct method is by chemical analysis of cadavers
Used only as a ‘gold-standard’ to validate a novel indirect method
Explain what a gold standard is
A method that has been tested and is the most reliable
What are the levels of body measurments?
Atomic - carbon, hydrogen, oxygen
Molecular - protein, lipid, water
Cellular - ECS (Concentration in extracellular solids), ECF (Concentration in extracellular fluids), Cells
Tissue - Blood, Bone, Adipose tissue, Skeletal muscle
Whole body
What is a DAPA model and the components of this model?
A class of interface models that use more than one source of measurement data to achieve a more valid estimate of body composition.
2-components - Fat mass (FM) and Fat-free mass (FFM)
3-components - Fat mass (FM), Water, Fat- free dry mass
4-components - Fat mass (FM), Water, Fat-free dry mass
5-components - Fat mass (FM), Water, Proteins, Bone mineral content (BMC), Non-osseous mineral content
6-components - Fat mass (FM), Water, Protein, Bone mineral content (BMC), Non-osseous mineral content, Glycogen
Explain what the following terms are composed of:
Fat mass
Fat-Free mass
Fat mass - includes water, protein, glycogen, bone mineral content, and non-osseous mineral content
Fat free mass - includes protein, glycogen, bone mineral content, and non-osseous mineral content
How useful are each of the body composition models?
1C - Not very useful for true ‘composition’ assessment, but vey simple and easy to carry out (e.g. BMI)
2C - Very commonly-used, Limited equipment needs, Simple conceptually, But makes lots of assumptions
3C and 4C- Less commonly used, Makes fewer assumptions, More sophisticated equipment, Greater conceptual complexity, Often used for special population where 2C assumptions are not valid
What are some of the challenges to measuring body composition?
Anorexic conditions
Osteoporosis
Oedematous conditions
Obesity
Artificial Ventilation
Cancer
Cystic Fibrosis
HIV/AIDS
Explain the term anthropometry
Anthropometry is the science that defines physical measures of a person’s size, from, and functional capacities.
Anthropometry literally means human measurements including: weight, height, circumference, limb length, Abdominal sagittal diameter, Skinfold thickness
Explain the method of hydro densitometry (underwater weighing) and give advantages and disadvantages
Method:
Measure ‘dry’ weight in air (kg)
Measure ‘wet’ weight (kg) when totally immersed in water
Calculations
Body density (g/ml) = Dry weight (kg) / difference
Example: 70kg / (70kg – 2.03kg) = 1.03 g/ml
Correction for residual volume of air in lungs and GI tract (very buoyant = 0.0012g/ml).
Often just assume an average value = 100ml
Advantages: very precise for normal, healthy population, reliable and accurate, often referred to as a ‘gold standard’ method
Disadvantages: Apparatus needed is substantial and not portable based on sex- and population-specific equations needed for good level of precision
Cannot assess fat distribution
Time and labour intensive
Explain what an air-displacement plethysmography is and give advantages and disadvantages of this method
Bodpod: the modern 2-C ‘gold standard’ method
Same principles to underwater weighing - displacement of air rather than water.
Still need to account for residual volume (lungs and GI tract).
Much more commonly used than UWW
Advantages:
Fast assessment time (2-5 mins)
Very accurate in healthy individuals
Minimal training required
Fits in a small room
Disadvantages:
Some people get claustrophobic, expensive to buy, reliant on 2-C assumptions
Explain what BMI is and the difference, advantages and disadvantages to this measurement method
BMI is an adult only measure
Women tend to have more body fat than men
Ethnicity/race - black people have less body fat than do white people, Asian people have more body fat than do whites
Older people, on average, tend to have more body fat than younger people
Athletes have less body fat than do non-athletes
Advantages:
Can be used in large-scale population studies
Inexpensive and simple to perform
Low measurement error
Can be used by GPs and clinicians
Useful for issuing public health recommendations
Secular trends (i.e. over time) can be easily observed and acted upon
Disadvantages:
Validity not so good for:
People with lower or greater-than-average muscle mass
Children: although BMI percentile charts are available, they’re much less predictive of BF than in adults
Elderly: changes in body composition with age
Non-European ethnic populations
Disease states and “abnormal” states (e.g. pregnancy and lactation)
Methods to measure weight on a person who cannot stand up
Wheelchair scale
Bed scale
Parachute/ lift
Explain what the Wait-Hip circumference is
The waist-hip ratio (WHR) is thee dimensionless ratio of the circumference of the waist to that of the hips. This is calculated as waist measurement divided by hip measurement
Explain what tricep skinfold measurements are
Sub- cutaneous fat depots around the body are measurements with callipers
Peripheral sites - biceps, triceps, thigh
Central sites = sub-scapular, supra-iliac
Site-specific skinfold measurements are often added up
Subcutaneous fat is related to total fat (more equations)
Age and gender-specific equations
Give advantages and disadvantages of triceps skinfolds
Advantages:
Relatively simple-to-use (once properly trained)
Relatively non-invasive
Highly portable (bedside possible)
Inexpensive to buy and operate
Can be used in healthy and sick populations
Disadvantages:
Inter-observer reliability is poor
Training required
Inaccuracies due to assumptions about subcutaneous fat
Population specific equations
How are the following measurements carried out:
Biceps skinfold
Triceps skinfold
Subscapular skinfold
Suprailia skinfold
Biceps skinfold - front side middle upper arm
Triceps skinfold - back side middle upper arm
Subscapular skinfold - under the lowest point of the shoulder blade
Super iliac skinfold - above the upper bone of the hip
Explain what a Bio-electric impedance machine is and give advantages and disadvantages
Measures the impedance/opposition to electrical flow
Impedance is low in lean tissue & high in fat
Impedance is proportional to body water volume
Advantages:
Machines are now relatively inexpensive
Machines are portable
Easy to standardise data across different sites
Operator can be trained in use in a few minutes
No need to undress
Results = comparable to DXA in certain populations
Disadvantages:
Prediction equations required and should ideally be population specific
Many machines use default equations, rather than more specific ones
Results can vary between makes and models
Reproducibility is affected by hydration state, fasting state, rapid body composition changes.
Explain how a dual-energy X-ray absorptiometry (DEXA) is used and give advantages and disadvantages
Body is scanned with x-rays of two different energy levels
Uses software to generate a 2-D picture
Imaging software calculates:
Bone mineral content and density
Lean mass
Fat mass
Vey useful for detection of osteoporosis, but also used extensively for obesity research
Advantages:
Relatively expensive £20,000
Uses assumptions
Disadvantages:
High reproducibility (0.5% variance bone mineral density & 2% total body comp.)
Radiation dose is relatively small
Quick & easy to perform
Subject friendly
When does measuring a high of a person not work?
If they have scoliosis or kyphosis or are disabled
Explain how ulna length is measured
Where possible, make measurements on the non-dominant side:
Ask the participant to stand straight facing you.
Ask them to raise their non-dominant arm so that their palm is across their chest, and their fingers are pointing upwards at the opposite shoulder
Using a tape measure, measure the distance between the olecranon (point of the elbow) and the styloid process (the prominent bone of the wrist).
Read the tape to the nearest 0.1 cm.
Record three measurements of ulna length and calculate the mean.
Height can be read from the table on the next page.
Explain how demi-span length is measured
Where possible, make measurements on the non-dominant side:
Ask the participant to stand straight facing you or sit upright
Demi-span (defined asthe distance between the mid-point of the sternal notch and the finger roots with the arm outstretched laterally)
Explain how Knee heigh is measured
The patient should bend their left knee and left ankle to a right angle
Hold the tape measure between 3rd and 4th fingers with a zero reading underneath fingers.
Place your hand about 4cm behind the front of the knee
Extend the tape measure straight down the side of the leg in line with the bony prominence at the ankle
Measure to the nearest 0.5cm
Explain how recumbent length is measured in infants
Infant or those under two years of age,should have height measured whilst they are lying down.
Measurement is from the top of the head to the soles (heels) of the feet.
What is a MUAC?
Mid-upper arm circumference
Explain what Xanthelasma is
Xanthelasma are yellow growths on or near the eyelids. They can be flat or slightly raised.
They form whendeposits of cholesterol (lipid or fat) build up under the skin.
Can be a sign of heart disease.
What is Glossitis?
Inflammation of tongue
What is Arcus Senilis
White or grey opaque arc shape around eyes
Visible around corneal periphery of the eyes
Associated with normal aging
Irreversible
